Tyrosinase inhibitory properties of phenylpropanoid glycosides and flavonoids from Teucrium polium L. var. gnaphalodes.

Abstract

In food industry, the inhibition of tyrosinase is very important, because this enzyme catalyzes the oxidation of phenolic compounds found in fruits and vegetables into quinones, which contribute in undesirable color and taste of fruits and vegetables. Teucrium polium L. var. gnaphalodes (Lamiaceae), a wild-growing flowering plant that has many applications in food preparations and traditional medicine. In Persian language, this medicinal herb is called Kalpoureh. 1D- and 2D-NMR experiments were used to determine the chemical structures of the isolated compounds. Antioxidant and tyrosinase inhibitory activities of the isolated compounds were evaluated using DPPH, FRAP and mushroom tyrosinase inhibition assays. In this research, we isolated two phenylpropanoid glycosides including verbascoside and poliumoside and two flavonoids including jaranol and isorhoifolin using chromatographic techniques. We found promising antioxidant and anti-tyrosinase compounds from Teucrium polium L. var. gnaphalodes. To date, different compounds have been isolated and characterized from T. polium including terpenoids and flavonoids. But no phytochemical study has been reported from T. polium var. gnaphalodes. Poliumoside and jaranol showed promising antioxidant and tyrosinase inhibitory activities, respectively.